You are here: Home Working Groups Prof. Dr. T. Bartolomaeus Team Dr. Julian Müller

Dr. Julian Müller


Julian Müller, 2018, Ziegler.jpg

Research focus

With approximately 21.000 described species, Annelida constitute a major taxon within the Lophotrochozoa. Transcriptomic and phylogenomic studies yielded an enormous progress in our understanding of their phylogeny, that forces to re-evaluate morphological characters. Under this aspect, my research focuses on the annelid’s chaetae, especially in basally branching taxa. Chaetae represent unique morphological characters, which are arranged in four bundles per segment and can be used for locomotion or defense mechanisms. They are built within a follicle, consisting of several invaginated epidermal follicle cells and one single chaetoblast, likewise of epidermal origin. The chaetoblast secretes chitinous material through its apical surface, where a distinct template of microvilli determines the shape of the chaetae. Properties of chaetae like topology, genesis and ultrastructure are interesting for determination and phylogenetic studies and thus, constitute a major aspect of my investigations.



  • Transmission electron microscopy
  • Light microscopy and 3D-modelling
  • Micro-computed tomography

Academic Qualifications

PhD thesis

Müller, J. (2022) Annelid chaetae - Ultrastructure, arrangement and phylogenetic significance. PhD Thesis, Uni Bonn.


Master’s thesis

Müller, J. (2018) Morphological and functional analysis of the rectal caecum, an enigmatic organ in the Schizasteridae (Echinoidea: Spatangoida). MSc Thesis, Uni Bonn.


Bachelor’s thesis

Müller, J. (2016) Topologie und Genese der Borsten bei Glycera gigantea (Glyceridae) und Nephtys hombergii (Nephtyidae) (Annelida). BSc Thesis, Uni Bonn.

Document Actions